1. Field
Embodiments described herein relate to a semiconductor memory device and a method of manufacturing the same.
2. Description of the Related Art
As a semiconductor device has been highly integrated recently, the circuit pattern of a transistor or the like constituting the semiconductor device is increasingly miniaturized. The miniaturization of the pattern requires not only a thinner line but also the increase in the size accuracy and position accuracy of the pattern. A semiconductor memory device requires the same.
Semiconductor memory devices that have been already known and commercially available such as DRAM, SRAM and flash memory use a MOSFET as a memory cell. Thus, with the miniaturization of the pattern, the pace of the improvement of the size accuracy needs to be more than that of the miniaturization. Thus, the difficulty of lithography technique to form the patterns causes the production cost to increase.
A resistance change memory has been recently gaining attention as a replacement for semiconductor memory devices using such a MOSFET as a memory cell. In the resistance change memory, a cross-point cell structure may be adapted, in which a memory cell is formed at the intersection of a bit line and a word line. Thus, the memory cell can be miniaturized more easily than the conventional memory cells and also can be stacked in a vertical direction. Accordingly, the memory cell array integration can be easily improved.
However, in a semiconductor memory device having such a cross-point cell structure, it is desirable to form an accurate wiring structure for connecting with the peripheral circuit without the risk of short-circuit or the like.